1. Field of the Invention
The present invention relates to disposable warmers such as disposable body warmers and disposable pocket warmers, and bag members for the disposable warmers. More specifically, it relates to disposable warmers having dramatically improved stretchability as compared to known equivalents; and bag members for the same.
2. Description of the Related Art
Disposable warmers of the type in which their bag is provided with an adhesive layer on one side thereof and which are attachable to any desired portion of the body (adhesive-patch body warmers) have been widely used without distinction of season, typically to warm easily and conveniently in winter and to prevent poor circulation and excessive sensitivity to cold in cooled environment in summer (refer typically to Japanese Unexamined Patent Application Publication (JP-A) No. Hei 10-314208; JP-A No. Hei 10-328224; JP-A No. 2000-42021; JP-A No. 2000-126217; JP-A No. 2000-288008; JP-A No. 2001-260293; JP-A No. 2002-36471; JP-A No. 2002-85442; JP-A No. 2002-113819; and JP-A No. 2002-127316). Such adhesive-patch disposable warmers are used as being applied typically to clothes such as socks, hose, and underclothes; footwear such as shoes and boots; and skin.
Known general disposable warmers have, for example, a structure as shown in FIG. 13. Specifically, this structure includes two bag members (a bag member 9 and a bag member 10), i.e., a top member and a back member, in which the two members are heat-sealed with a heat sealing device to form a bag, and a heater 3 mainly including, for example, iron powder is sealed in the bag. The bag member is provided with a pressure-sensitive adhesive layer 4 to be attached to an adherend. Examples of the bag member include (1) a multilayer member as a layered material of an air-permeable porous base film and a nonwoven fabric layer; and (2) a multilayer member as a layered material of a heat-sealable airtight base film and a nonwoven fabric layer.
However, base films used in bag members of the disposable warmers generally have poor stretchability, whereby the known disposable warmers have poor stretchability and unsatisfactory wearing comfort. With increasing requirements therefor, disposable warmers should have high stretchability so as to attach easily and conveniently and to wear comfortably.
To solve these problems, there is known a technique of providing slits 105b (cuts or notches) at edges of a disposable warmer, which slits 5b pierce the warmer in a thickness direction, as illustrated in FIG. 14. This technique provides a disposable warmer that extensionally deforms to some extent. However, the warmer is stretchable only to such an extent that the slits deform and thereby still has insufficient stretchability. In other words, this technique fails to provide a sufficiently stretchable body warmer. In contrast, a disposable warmer, if provided with relatively large piercing slits, has poor strength.